A “thin section” of rock is a sample that is mounted to a microscope slide and cut so thin that you can see light through it. The process of creating a thin section is a blend of artistry, technology and science.
The art of preparing thin sections has been critical to understanding the core samples that scientists are observing. Thin section samples allow scientists to observe minerals in rocks, their crystal structure and texture at a microscopic level.
Want to revise how do geologists study rock? Follow this link to see our blog on "Studying Rock".
In this blog, we're taking you into the journey of thin section photos that were captured and given by students and young professionals from Finland, Ireland, Denmark, Czech Republic and Plymouth (UK).
Again our purpose is to encourage students and professionals' research by promoting "learning and scope" of Geology through our blogs. Help us to help others in learning and understanding geology. See this link that how you can contribute to Learning Geology.
Note: We are using following thin section photos by having permission from their owners. If you like to use these photos, leave us a message or email us here.
1. A beautiful heart shaped hornblende in XPL (cross polarized light) view.It is a thin section of basalt with some secondary mineralization in the vesicles. Plagioclase is present in the form of black and white matrix and large phenocryst (with some zoning). Alignment of plagioclase grains is indicative of the "flow" of magma.
2. Thin Section of a Biotite and Muscovite, XPL view
3. Thin Section of a Plagioclase (orthoclase) and Pyroxene, XPL
4. Eclogite in Thin Section, XPL
5. Cummulate Rock with Pyroxene and plagioclase, XPL
6. Blueschist, XPL
7. Agglomerate in a Thin Section, XPL view
Agglomerates are pyroclastic igneous rocks that consist almost wholly of angular or rounded lava fragments of varying size and shape. Fragments are usually poorly sorted in a tuffaceous matrix, or appear in lithified volcanic ash. (Britannica.com)
8. Thin Section of a Pigeonite and Olivine, XPL
9. Olivine phenocryst in Basaltic Lapilli, XPL
10. Thin Section of a Gabbro, XPL
Showing minerals; Pyroxene and Olivine, plagioclase and others. Learn more about Gabbro here.
11. Another beautiful thin section of a Gabbro, XPL
12. Thin Section of a Greenschist, XPL
13. Thin Section showing intrusion of rocks from magma chamber into country rocks, XPL
14. Thin Section of a Sillimanite - a mineral found in rocks formed by the metamorphism of a mudstone. (XPL view)
15. Microgeode in ultrabasic vulcanite (a rare copper telluride mineral), 30 µm thin section, PPL and XPL
16. Muscovite & biotite (30 µm thin section, PPL and XPL)
 |
Photo Courtesy: Petr Hyks
Same photo in XPL view. See original photo here |
17. Quartz and epidote (30 µm thin section, PPL and XPL)
18. Olivine (30 µm thin section, PPL and XPL)
 |
Photo Courtesy: Petr Hyks
See this photo here on Petr Hyks' website |
19. Zircons in biotite (30 µm thin section, PPL views, showing extinction)
20. Zircon in biotite (30 µm thin section, XPL)
21. Kyanite surrounded by muscovite (30 µm thin section, PPL and XPL)
22. Zircon crystal in chloritized biotite (30 µm thin section, PPL and XPL)
Petr Hyks is 21 year old geology student from Masaryk University in Brno (Czech Republic). He has uploaded 5000+ photos about geology, astronomy and meteorology on his Flickr page. Follow this link to visit his website. Thank you Petr for contributing to Learning Geology and helping others to learn geology through your thin section photos. 🙂 Now following 10 thin section photos are from a geology student of University of Helsinki, Finland.
23. Thin Section of Olivine Diabase in XPL and PPL view.
24. Thin Section of Basalt in XPL view
Having minerals: Olivine (in center) plagioclase, pyroxene and other accessory minerals
25. Thin Section of a Trachyte, XPL view
Trachyte is an igneous volcanic rock with aphanitic to porphyritic texture. It is volcanic equivalent of Syenite. Major or essential minerals are alkali feldspar with less amount of plagioclase, quartz or feldspathiod.
26. Thin Section of a Harzburgite, XPL view
Harzburgite is an ultramafic igneous rock. It chiefly contains plagioclase (under 10%) , olivine, orthopyroxene (enstatite), clinopyroxene (diopside) and biotite. There could be a small amount of talc, carbonate, tremolite, cummingtonite, chlorite, serpentine and titanite.
27. Another thin section of Harzburgite, XPL view
28. Thin Section of Pyroxenite (an ultramafic igneous rock), XPL view
29. Thin Section of Trachyte showing Sandine mineral in center, XPL view
30. Thin Section of Andesite, XPL view
It is an extrusive igneous, of intermediate composition, with aphanitic to porphyritic texture. Here this thin section is showing chiefly hornblende and plagioclase.
31. Thin Section of Alkali Basalt (silica undersaturated) in XPL view.
32. Thin Section showing small clinopyroxene grains within orthopyroxene
Like this article? Leave a comment down or send us your valuable suggestion or feedback here to help us in improving this article.
Useful Websites:
1. Polarized light Microscopy (Image Gallery)
2. How to make a thin section
3. Petrographic thin section preparation
4. Guide to Thin Section Microscopy
5. Index of Minerals in Thin Section
6. Optical Petrography website by an Italian Geologist
7. Carbonate Thin Section Images and Exercises
